1978 R100RS final drive

[jsey]

Hi all,
Was recently changing all of my rusty fill and inspection plugs on the swing arm and final drive on my 1978 R100RS. Part number 11 13 1744329 (final drive inspection plug 8mmx1.0) doesn't seem to be part of my final drive housing assembly. What is part of my assembly is a hole just to the right of the 18mm x 1.5 final drive fill plug. The unthreaded hole goes clear through to the other side of the housing and was plugged off with a plastic plug (which disintegrated upon touching it). When you look through it you can see the rear wheel hub rotating. This plastic plug isn't shown or mentioned in the Micro-Fische parts breakdown. The question is where can this plug be sourced and what is the hole actually for? Thanks

 

[jsey]

Just occurred to me that the hole may be a final drive housing meant for a drum brake that was converted to disc. I do have a rear disc brake. Whether this was done at the factory or elsewhere is a mystery

 

[fmdualexhaust]

Just for you I pulled out my file.
My bike was exactly like yours.
It is called a blind plug.
Part # 33 11 1 236 826

I got mine at Max BMW
$2.25 each.

 

[stevenrankin]

Yep

Yep, that plug is to plug the hole used for the drum brake shaft. There is no pressure there no fluid to worry about so just about any kind of plug can be used to plug the hole. As FM says, Max has the proper plug. St.

 

[jsey]

Just for you I pulled out my file.
My bike was exactly like yours.
It is called a blind plug.
Part # 33 11 1 236 826

I got mine at Max BMW
$2.25 each.

Thanks

 

[jsey]

Yep, that plug is to plug the hole used for the drum brake shaft. There is no pressure there no fluid to worry about so just about any kind of plug can be used to plug the hole. As FM says, Max has the proper plug. St.

Thanks